diff --git a/packages/node_modules/node-red/red.js b/packages/node_modules/node-red/red.js
index 2f5ab354c..22b1eb224 100755
--- a/packages/node_modules/node-red/red.js
+++ b/packages/node_modules/node-red/red.js
@@ -316,10 +316,10 @@ httpsPromise.then(function(startupHttps) {
             } else {
                 continue;
             }
-            sp.subRoot = formatRoot(sp.root);
+            sp.subRoot = formatRoot(sp.root || "/");
             sp.root = formatRoot(path.posix.join(settings.httpStaticRoot,sp.subRoot));
         }
-        settings.httpStatic = sanitised.length ? sanitised : false;    
+        settings.httpStatic = sanitised.length ? sanitised : false;
     }
 
     // if we got a port from command line, use it (even if 0)